1. Field of the Invention
This invention relates to reducing a magnetic noise of a vehicular alternating current generator.
2. Discussion of Background
FIG. 7 is a sectional diagram in the axial direction showing a conventional motor which has been disclosed in Japanese Unexamined Patent Publication No. 254050/1986, and FIG. 8 is a sectional diagram taken along the line VIII--VIII of FIG. 7.
In FIGS. 7 and 8, numeral 1 designates a stator core which is supported in a stator frame 2, and which is wound with a coil 3 by, for instance, random winding. Numeral 4 designates a rotor, and numeral 5 designates a rotating shaft of the rotor 4, which is supported by brackets 7 through bearings 6. Numeral 8 designates a slot formed in the stator core 1, wherein the coil 3 is accommodated through a U-shaped slot insulation 9 and the departure of the coil from the slot is prevented by a wedge for slot 10.
Next, an explanation will be given of the operation. The rotor 4 and the rotating shaft 5 are rotated by an electromagnetic force which is generated by supplying power to the coil 3.
Since the conventional motor is constructed as above, when an alternating current flows in the coil 3, the stator core 1 and the coil 3 are excited to vibrate by an electromagnetic force operating between the stator core 1 and the rotor 4 and an electromagnetic force generated in the coil 3, whereby a magnetic noise is generated.
As a method of reducing the magnetic noise, there are a method of reducing the electromagnetic forces each of which is an exciting force, a method of increasing a rigidity of an excited portion (mainly stator core 1) and the like. There is a problem of a reduction in capacity in the former method and there is a problem of an increase in weight and an enlargement in physical construction in the latter method.